// Copyright (c) Appeon. All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. 
// You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.

using System;
using System.Data;
using System.Data.Common;
using JetBrains.Annotations;

namespace SnapObjects.Data.Odbc
{
    public class OdbcAseStringTypeMapping : OdbcStringTypeMapping
    {
        private const int DEFAULT_SIZE = 8000;

        /// <summary>
        ///     Initializes a new instance of the <see cref="OdbcStringTypeMapping" /> class.
        /// </summary>
        /// <param name="dbTypeName"> The name of the database type. </param>
        /// <param name="dbType"> The <see cref="DbType" /> to be used. </param>
        /// <param name="unicode"> A value indicating whether the type should handle Unicode data or not. </param>
        /// <param name="size"> The size of data the property is configured to store, or null if no size is configured. </param>
        public OdbcAseStringTypeMapping(
            [NotNull] string dbTypeName,
            [CanBeNull] DbType? dbType,
            bool unicode = false,
            int? size = null)
            : base(dbTypeName, dbType, unicode, size)
        {
            _maxSpecificSize = CalculateSize(unicode, size);
        }

        /// <summary>
        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public override TypeMapping Clone(string dbTypeName, int? size)
        {
            return new OdbcAseStringTypeMapping(dbTypeName, this.DbType, this.IsUnicode, size);
        }

        /// <summary>
        ///     This API supports the Entity Framework Core infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        protected override void ConfigureParameter(DbParameter parameter, IAdoDbParameter adoDbParameter)
        {
            // For strings and byte arrays, set the max length to the size facet if specified, or
            // 8000 bytes if no size facet specified, if the data will fit so as to avoid query cache
            // fragmentation by setting lots of different Size values otherwise always set to
            // -1 (unbounded) to avoid SQL client size inference.

            var value = parameter.Value;

            var length = (value as string)?.Length ?? (value as byte[])?.Length;

            if (parameter.Direction == ParameterDirection.Output ||
                parameter.Direction == ParameterDirection.InputOutput)
            {
                parameter.Size = _maxSpecificSize;
            }
            else
            {
                parameter.Size = value == null || value == DBNull.Value || (length != null && length <= _maxSpecificSize)
                    ? _maxSpecificSize
                    : -1;
            }
        }

        private static int CalculateSize(bool unicode, int? size)
        {
            if (unicode)
            {
                return size.HasValue && size <= 8192 ? size.Value : 8192; // unicode's length is same
            }
            else
            {
                return size.HasValue && size <= 16384 ? size.Value : 16384; // unicode's length is same
            }
        }
    }
}
